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United States Patent 26,613 HIGH TENACITY RAYON YARN PRODUCTION GeertAntema, Tietso Kuipers, and Johannes J. M. Mulderink, Arnhem,Netherlands, assignors to American Enka Corporation, Enka, N.C., acorporation of Delaware No Drawing. Original No. 3,364,290, dated Jan.16, 1968, Ser. No. 318,838, Oct. 25, 1963. Application for reissue May14, 1968, Ser. No. 729,136 Claims priority, application Netherlands,Oct. 30, 1962 Int. Cl. Doll 3/28 U.S. Cl. 264-197 8 Claims Matterenclosed in heavy brackets II] appears in the original patent but formsno part of this reissue specification; matter printed in italicsindicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE Manufacture of high tenacity rayon yarnscomprising the process of extruding a viscose containing a skinproducingmodifier [and a cation-active compound which counteracts the occurrenceof spinning faults] into a spin bath containing sulfuric acid, sodiumsulfate and zinc sulfate, stretching the yarn in a hot dilute acid bath,adjusting the yarn to a pH of from to 8.5, collecting the yarn in theform of a cake, unwinding the yarn from the cake, after-stretching anddrying the yarn for a maximum of 20 minutes.

This invention relates generally to the production of rayon filamentarymaterials suitable for use as reinforcement in tires, belts and otherrubber articles and more particularly to a process for producing extrahigh tenacity threads, yarn, and cord and regenerated cellulose.

The known process for producing high tenacity regenerated cellulosethreads, yarn and cord, hereinafter referred to collectively as yarn,comprises extruding a viscose in the presence of a skin-producingmodifier, into a spinning bath containing sulfuric acid, sodium sulfate,and 3 to 10% by weight of zinc sulfate, stretching the freshly spun yarnin a hot bath containing dilute acid, collecting and winding thestretched yarn in package form, and drying the yarn in the package orunwinding and drying it continuously. The thus produced yarn has a hightenacity, each filament having a high skin structure when viewed incross section.

It has been found that rayon yarn of even higher tenacity than thatproduced by the aforementioned process is desirable for many present dayapplications. In this respect then, while the known high tenacity yarnis generally good, it is necessary that even higher tenacity yarn beproduced.

Accordingly, it is an object of this invention to provide a process forproducing rayon yarn having improved properties.

Another object of this invention is to provide a process for producingextra high tenacity rayon yarn.

Still another object of this invention is to provide a process forproducing extra high tenacity yarn of regenerated cellulose that can becarried out in conjunction with the known process with a minimum ofadditional steps and attendant expense.

These and other objects will become more apparent from the followingdetailed description.

In accordance with the present invention, extra high tenacity rayon yarnis produced by modifying the aforementioned known process with twocritical steps. in essence, this comprises adjusting the extruded yarnto a pH of 5 to 8.5 after stretching in the hot acid bath and beforewinding, followed by limiting the drying process to a. maximum of 20minutes.

SEARCH ROOM Reissued June 24, 1969 There are several methods ofadjusting the freshly spun wet yarn to a pH of 5 to 8.5. A very simplemethod consists in washing the running wet yarn with water. If water isused having a temperature of 13 C. or higher, then it is preferred toprolong the treatment of the wet yarn until they no longer contain saltsand the pH of the yarn is about 7. If cold water is used, i.e., 12 C. orlower, then the wet yarn need not be treated until it is free fromsalts.

The pH of the yarn is determined as follows: 200 cc. distilled water ispoured over 6 grams of the wet yarn (containing about moisture) in abeaker. The yarn is allowed to stand in the beaker for one hour, withoccasional shaking, after which the pH of the liquid is measured,thereby determining the pH of the yarn.

In addition to water, the, treatment of the wet yarn can be carried outwith an aqueous salt solution such as sodium carbonate, sodiumbicarbonate, or sodium sulfate. An aqueous solution of ammonia may alsobe used. If the temperature of the washing liquid is 12 C. or lower,then the yarn need not be washed as thoroughly as when the temperatureis 13 C. or higher. The treatment of the wet yarn with water,salt-containing water, or ammoniacal water may be carried out by passingthe yarn through a bath. As pointed out above, however, it is criticalthat this step be carried out before the yarn is wound and collected inpackage form. Alternately, the liquid can be sprayed on the godet overwhich the yarn is passed to the collecting device.

After the wet yarn has been treated so that its pH is from 5 to 8.5, itis collected in a yarn package such as in a spinning pot, perforatedbasket, or on a spool. It is thereafter dried and, as mentioned above,the drying process must not last longer than 20 minutes. A drying periodof any longer duration has a very unfavorable influence on the tenacityof the yarn. Drying may be carried out by several ways, such as byplacing the wet yarn package in a high-frequency electric field, or byunwinding the wet yarn from the package and drying it with hot air whiletraveling through a drying tunnel. It also may be done by passing thewet yarn over a hot roller.

The yarn should be kept under tension during drying. This may beeffected in various ways. After treatment with the washing liquid, thewet yarn may be wound under tension on a spool and the yarn packagedried in a high-frequency field. Also, after the treatment with thewashing liquid, the running wet yarn can be guided under tension througha drying tunnel or over a hot roller. In an alternate system, the wetyarn may be unwound from a yarn package, after-stretched, andsubsequently dried.

In a typical process according to the invention, a viscose is spun inthe presence of at least one compound which will produce a skinstructure in the threads. For the sake of brevity, such compounds arehereinafter referred to as modifiers. The modifier may be present in theviscose or in the spin bath, or in both. A number of known modifiers canbe used in the process, such as amines, quaternary ammonium compounds,carbaminates, polyethylene glycol, and ethers having the formulaRO(CH,CH 0),,R', where R is an alkyl or aryl group, R is hydrogen, analkyl or aryl group, and n is 1-4 incl. Specific examples of amines arecyclohexylamine, quinoline, ethylene diamine, hexamethylene diamine,dipropylene triamine, dodecylamine, and dibutylan'iinopropylamine.Examples of quaternary ammonium compounds are benzyltrimethylammoniumhydroxide, tetraethylammonium hydroxide, tetraethylammonium bromide,tetraethylammonium iodide, and tributylpropylammonium peroxide.Representative carbaminates are sodiumcyclohexyldithiocarbaminate,sodium phenyldithiocarbaminate, sodium morpholyl-N-dithiocarboxylate,and sodium-cyclohexylmonothiocarbaminate. The polyethylene glycol mayhave an average molecular weight of 200 to 4,500. Examples of ethers arephenoxyethanol, ethoxyethanol, methoxyethoxyethanol, andbutoxyethoxyethanol. The modifiers may be used singly or in combination.

For best results, it is also preferred to spin the viscose in thepresence of a compound which counteracts the occurrence of spinningfaults. These are usually cationactive compounds, for example,laurylpyridinium chloride, stearylpyridinium chloride,dodecyltriethylammonium iodide, and compounds having the formula:

(CslItOhII c,tI.0),H where R is an alkyl group having 8 to 24 carbonatoms, x and y are at least 1, and x+y is 5 to 25. Preferably, a viscoseis used containing the last mentioned compound in combination withpolyethylene glycol. The viscose contains each of these two substancesin amounts of at least 0.5% by weight, based on the cellulose in theviscose, with the nitrogen compound being derived from soy bean oil,coconut oil, or tallow and where x plus y is about 12.

When using these two compounds in combination, the yarn obtained hasoptimum strength if the viscose employed has a cellulose content of 6 to8% by weight, a total alkali content of 5 to 6% by weight, and aHottenroth maturity index of 13 to 18. The viscose should then beextruded into a spin bath maintained at 40 to 60 C., having a sulfuricacid content in percent by weight which is 0.83 to 0.95 times the totalalkali content in percent by weight of the viscose, a sodium sulfatecontent of 11 to 15% by weight, and a zinc sulfate content of 3 to 5% byweight. The yarn is then successively stretched about 100% in a dilutesulfuric acid bath maintained at about 95 C., washed with water until itis free of acid and salts, and collected in the form of a cake in aspinning pot. The yarn is then unwound from the cake and after-stretchedabout It is subsequently dried on a hot roller and thereafter wound inpackage form.

To further illustrate the invention, the following examples are given.However, the invention is not intended to be limited thereby. Allpercentages are by weight unless otherwise stated.

Example I A viscose is prepared having a cellulose content of 7.3%, atotal alkali content of 5.5%, a viscosity of 110 seconds (ball fallmethod), and containing 1.5% by weight (basedonthe cellulose in theviscose) of polyethylene glycol having an average molecular weight of3,000, and 1.5% by weight (based on the cellulose in the viscose) of acompound having the formula:

(C H40] I where R is an alkyl radical derived from coconut oil, and x+yis 12. The viscose was aged to a y-number of 45 and a Hottenrothmaturity index of and spun into a bath maintained at 50 C. containing4.9% sulfuric acid, 13% sodium sulfate, 4.5% zinc sulfate, 0.004%laurylpyridinium chloride, and 0.025% of a compound having the formula:

:H4 )rH R-N\ customs where R is an alkyl radical derived from coconutoil, and x+y is 12. The spinneret had 1,000 orifices, each having adiameter of 60 The yarn emerging therefrom was guided through a tubeimmersed in the spin bath which consisted of two cylindrical sections,one section (near the spinneret) having an inner diameter of 16.5 mm.and the second having an inner diameter of mm.

The yarn was taken up by means of a godet at 30 m./min.

After the yarn had left the spin bath, it was passed through a secondbath maintained at C. containing 2.5% sulfuric acid, 1% sodium sulfate,and 0.5% zinc sulfate. In this bath the yarn was stretched by means of asecond godet, the speed of which was twice that of the first godet.Water at 30 C. was sprayed on the second godet. After the yarn had leftthe second godet, it had a pH of 7.5 and was collected in a spinningpot. It had obtained a twist of 100 S turns per meter. The thus producedyarn was then drawn off the cake in the wet state and guided through awater bath containing 3% liquid paraffin, 0.3% butyl stearate, and 0.4%sulfated peanut oil. In this bath the yarn was after-stretched about 10%and then dried in half a minute by guiding it, under tension, over a hotroller. The resulting yarn had a denier of 1,650 and was wound onto aspool.

The yarn was conditioned in air at 20 C. and 60% relative humidity andhad a strength of 9.6 kg. Desulphurization, washing and dryi'hg of theyarn did not produce any decrease in strength. Thereafter, the yarn wastwisted 470 S turns per meter. Two such yarns were plied together with470 Z turns per meter to produce a tire cord that had, in theconditioned and bone-dry state, a strength of 15.1 and 18.5 kg.,respectively.

Example II The process of Example I was repeated, except that the yarnwas not treated with water on the second godet. After the yarn had beencollected in the spinning pot, it was desulphurized and washed.Subsequently, the yarn was after-stretched by about 10% in the sizingbath and then dried. The conditioned strength of the yarn was 8.2 kg.,considerably lower than that of the yarn obtained in the processdescribed in Example I. The conditioned strength and the bone-drystrength of tire cord made from two such yarns were 13.5 and 15.9,respectively.

Example III The process of Example I was repeated, except that on thesecond godet the yarn was sprayed with water at 12 C. After the yarn hadbeen collected in the spinning pot, it was successively desulphurized,washed, afterstretched by about 10% in the wet state, dried on a hotroller, and wound. The conditioned strength of the yarn was 9.6 kg. Theconditioned strength and the bonedry strength of tire cord made from twosuch yarns were 15.0 and 18.4 kg., respectively.

Example IV The process of Example I was repeated, except that on thesecond godet the yarn was sprayed with an aqueous sodium bicarbonatesolution until it reached a pH of 8.5. After the yarn had been collectedin the spinning pot, it was successively desulphurized, washed,afterstretched by about 10% in the wet state, dried on a hot roller, andwound. The conditioned strength of the yarn was 9.5 kg. The conditionedstrength and the bone-dry strength of the tire cord made from two suchyarns were 15.1 and 18.4 kg., respectively.

Example V The process of Example I was repeated, except that the viscosecontained 2% by weight (based on the cellulose in the viscose) quinolineand 1% by weight (based on the cellulose in the viscose) of a compoundhaving the formula:

where R is an alkyl radical derived from coconut oil and x+y is 12. Theconditioned strength of the yarn was 9.4 kg. The conditioned strengthand the bone-dry strength of tire cord made from two such yarns were14.9 and 18.2 kg., respectively.

Example VI The process of Example I was repeated, except that theviscose contained 1.5% by weight (based on the cellulose in the viscose)of a compound having the formula:

where R is an alkyl radical derived from coconut oil and x-l-y is 12,and 1.5% by weight (based on the cellulose in the viscose) of a compoundhaving the formula:

(carom:

where R is an alkyl radical derived from coconut oil and x+y is 12. Theconditioned strength of the yarn was 9.2 kg. The conditioned strengthand the bone-dry strength of tire cord made from two such yarns were14.8 and 18.0 kg., respectively.

Many modifications and changes within the scope of this invention willbe apparent to those skilled in the art. Accordingly, the invention isintended to be limited only to the extent set forth in the followingclaims.

What is claimed is:

1. In a process for producing high tenacity rayon yarn, the combinationwhich comprises:

(a) extruding a viscose containing at least one skinproducing modifierselected from the group consisting of an amine, a quaternary ammoniumcompound, a carbaniate, a polyethylene glycol and an ether having aformula RO( CH CH O R where R is selected from the group consisting ofalkyl and aryl radicals, R is selected from hydrogen,

alkyl and aryl radicals and n is 1-4 in combination with a cation-activecompound which counteracts an occurrence of spinning faults, saidcatiomactive compound being selected from the group of laurylpyridiniumchloride, stearylpyridinium chloride, dodecyltriethylammonium iodide andcompounds having the formula (C 11110) H RN\ where R is an alkyl grouphaving 8 to 24 carbon atoms and x+y is to 25,

(b) into a spin bath being maintained at 40-60 C. having a sulfuric acidcontent in percent by weight which is 0.83 to 0.95 times the totalalkali content in percent by weight of the viscose, a sodium sulfatecontent of 11 to 15% by weight and a zinc sulfate content of 3 to 5% byweight,

(c) successively stretching the yarn about 100% in a dilute sulfuricacid bath maintained at about C.,

(d) adjusting the yarn to a pH of from 5 to 8.5 and collecting the yarnin the form of a cake,

(e) unwinding the yarn from the cake, and

(f) after-stretching the yarn about 10% and drying for a maximum of 20minutes.

2. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with water.

3. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with an aqueous salt solution.

4. The process of claim 1 in which the pH of the yarn is attained bytreating the yarn with an aqueous ammonia solution.

5. The process of claim 1 in which the yarn is dried while undertension.

6. The process of claim 1 in WfllCh the viscose contains as modifiers atleast 0.5% by weight based on the cellulose in the viscose ofpolyethylene oxide and at least 0.5% by weight based on the cellulose inthe viscose of a compound having the formula:

where R is an alkyl radical containing from 8 to 24 carbon atoms andx-l-y is 5-25.

7. The process of claim 1 in which the yarn is afterstretched about 10%and dried on a hot roller.

8. In a process for producing high tenacity rayon yarn the combinationwhich comprises:

(a) extruding a viscose containing at least one skinproducing modifierselected from the group consisting of an amine, a quaternary ammoniumcompound, a carbamate, a polyethylene glycol and an ether having theformula where R is selected from the group consisting of alkyl and arylradicals, R is selected from hydrogen, alkyl and aryl radicals and n is1-4;

(b) into a spin bath being maintained at 40-60 C. and having a sulfuricacid content in. percent by weight which is 0.83 to 0.95 times the totalalkali content in percent by weight of the viscose, a sodium sulfatecontent of 11 to 15% by weight, a zinc sulfate content of 3 to 5% byweight and including a cationactive compound being selected from thegroup of laurylpyridinium chloride, stearylpyridinium chloride,dodecyltriethylammonium iodide and compounds having the formula (CgHtOhH(CsH|O),H

where R is an alkyl group having 8-24 carbon atoms and x+y isS to 25;

(c) successively stretching the yarn about in in a dilute sulfuric acidbath maintained at about 95 C.;

(d) adjusting the yarn to a pH of from 5-8.5 and collecting the yarn inthe form of a cake;

(e) unwinding the yarn from the cake and,

(f) after-stretching the yarn about 10% and drying for a maximum of 20minutes.

7 8 References Cited 2,983,572 5/1961 Elling et a1. 264194 X Thefollowing references, cited by the Examiner, are 3,007,766 11/1951Elsner et a1 264194 X of record in the patent filed of this patent orthe original 3,046,082 7/1962 Mltchell 3L 264194 X patent 3,046,0857/1962 Burroughs et a]. 264-497 X UNITED STATES PATENTS 5 JULIUS FROME,Primary Examiner.

2,512,968 6/1950 Ray 264197 2,611,928 6/1952 Marion 254-491 WOO,Assistant Examiner 2,602,258 12/1952 McLellan 264198 Us Cl XR 2,852,3339/1958 Cox et al. 264-198X 2,914,376 9/1959 Bibolet et a1. 264-193X8130.1; 106-165; 264-191, 192, 193, 194, 195

2,978,292 4/1961 Limburg et a1 264194 X

